渗透侵蚀下砂性土细颗粒流失率预测方法

渗流过程中内部不稳定砂性土细颗粒易于流失而形成渗透侵蚀,将对土工建筑物或地基造成不良影响。细颗粒流失率是土体力学性能劣化及稳定性分析的关键参数,为了对渗透侵蚀下砂性土细颗粒的流失率进行预测,笔者讨论了判断土体是否会发生渗透侵蚀的内部稳定性评价准则;介绍了细颗粒起动临界坡降,并对应力折减系数进行修正,以考虑土颗粒受力的差异性;提出了“细颗粒起动概率”,对细颗粒起动与否进行量化;分析细颗粒在土体孔隙网络中的迁移过程,给出了细颗粒通过收缩的概率和渗透迁移距离;根据细颗粒起动和迁移规律给出了细颗粒侵蚀和沉积定律,基于质量守恒定律形成细颗粒流失率预测方法。采用预测方法进行流失率计算,计算结果和试验结果吻合较好,误差基本在15%以内。

Prediction Method for Fine Particle Loss of Sandy Soil under Seepage Erosion

In the process of seepage, the internal unstable sandy soil fine particles are easy to be lost and form seepage erosion, and it will have a bad effect on the geotechnical building or foundation. The loss rate of fine particles is a key parameter for soil mechanical property degradation and stability analysis. In order to predict the loss rate of fine particles in sandy soil under seepage erosion, the internal stability evaluation criteria for determining whether soil will undergo seepage erosion was discussed firstly. This paper introduced the critical starting slope of fine particles, modified the stress reduction coefficient to take into account the difference of soil particles' forces, and introduced the “starting probability of fine particles” to quantify the starting of fine particles. The migration process of fine particles in the pore network of soil was analyzed, and the probability of fine particles through shrinkage and the migration distance through permeability were given. According to the law of fine particle starting and migration, the law of fine particle erosion and deposition was given, and the prediction method of fine particle loss rate was formed based on the law of mass conservation. The prediction method was used to calculate the rate of loss. The calculated results are in good agreement with the test results, and the error is basically within 15%.